Allows users to assign categories (or other taxonomy terms) to items in their Media Library with a clean and simplified, searchable version of the standard category meta box.
The "Search Categories" field allows you to narrow your search for a category as you type - this functionality is not native to WordPress but is instead borrowed from Jason Corradino's
Searchable Categories plugin. If you would like to enable this feature for your posts
download his plugin here

Since WordPress 3.5 now supports attachment taxonomy, the work of adding a metabox to the attachment editor is happening entirely inside of WordPress. This is great, and we now have true metaboxes for taxonomy - they core team has also accepted my patches which caused several headaches for this plugin. Media Categories 1.5 takes advantage of the new Media Modal - with this plugin, you can now edit a images categories directly from the modal screen. I've also fixed some long standing bugs with the shortcode gallery functionality.

Updates

Since version 1.5 : Supports the new WordPress 3.5 by adding the metabox to the new Media Modal. Also fixed bugs in the gallery shorcode behavior. All while still supporting 3.3.x - 3.4.x

Since version 1.4 : This plugin allows for multiple metaboxes to be created for any number of taxonomies.

Since version 1.3 : A filter has been added to allow developers to modify which taxonomy is being used. See 'Other Notes' > 'Taxonomy Filter Usage' for details

Since version 1.2 : This plugin extends the native [gallery] shortcode of WordPress so that it has a 'category' parameter. See the "Shortcode Usage" under "Other Notes" for more details.